1. Technical Field
The present invention relates to an improved mechanism for an automated self-propelling endoscope.
2. Discussion of the Related Art
The flexible fiberoptic colonoscope has provided direct visualization of the inner surface of the entire colon, and has greatly influenced the diagnosis and treatment of colonic diseases over the past three decades. It is pervasively used throughout the U.S. and much of the industrialized world. It provides information that is complementary to common radiologic, CT scan, MRI, and other sophisticated imaging scanning techniques in the diagnosis of colonic disease, and in many circumstances it is considered to provide the most reliable, efficient and effective available tool. Via instruments inserted through channels in the scope, a wide array of diagnostic and therapeutic instruments can be used. However, a major impediment to colonoscopy is the long time that often is required to examine the full length of the colon. The introduction of the scope is in a direction opposite to that effected by normal peristaltic waves. Further, the tubular colon is tortuous and highly flexible, and its walls often fail to direct and guide the scope as it is moved into the colon. As the scope is manually propelled, it enters loops of colon that become “cul-de-sacs” which trap the leading end of the scope, and prevent the desired retrograde movement of the scope through the lumen. Advancing the scope is reminiscent of attempts to “push a chain or a flexible rope”. With only manual insertion efforts, progression of the distal end of the scope into the colon is successful for the first few short distances; but as the length of penetration increases and tortuous configurations of bowel need to be negotiated, the difficulties increase greatly, even with visual directional guidance of the tip of the scope. The endoscopist uses a variety of maneuvers to nudge the scope further, including repeatedly repositioning the patient (and the colon); utilizing gravity effects to move the heavier leading end of the scope “downhill”; manipulating the scope against the bowel wall to round corners; applying pressure on the external abdomen; altering the rigidity of segments of the scope to more effectively translate push-effects distally; changing lumen size and configuration with air insufflation; etc. However much endoscopists do succeed in traversing the entire colon, there is clearly need for mechanisms to facilitate the process and to hasten its accomplishment. Many examinations require much time, and many are terminated before the examination is complete. Thus, a mechanized process that would allow rapid retrograde propelling of the scope to the cecum would be of great value. Colonoscopic examinations are costly, and part of this is due to the amount of professional time required for the complete examination. In summary, were an automated mechanism available to facilitate rapid traversal of the colon, it would increase both the effectiveness and efficiency of the wide range of diagnostic and therapeutic uses of the procedure, and contribute to reducing the financial cost of the procedure.
The essence of the problem is to develop a mechanized propelling system that is self-contained in the instrument that does not depend upon the external guidance effect of the surrounding highly flexible tubular bowel. Force to insert the colonoscope through the anus into the patient is simple and straightforward. What is needed is some array of technology that would simulate the actions of a “virtual hand” that was located in the lumen of the colon just ahead of the tip of the endoscope, and could grasp and pull the tip in the direction of the lumen toward the proximal colon. This is akin to a “Maxwell's demon's hand” that could and would “knowingly” act as needed.
An analogous problem exists for the small bowel endoscope (enteroscope). The small bowel is about 30 feet long and telescopes itself on introduced instruments. It may take several hours for an enteroscope to traverse major portions of the small bowel. As a result, this is a rarely used procedure.
Some characteristics of a conventional fiberoptic endoscope (colonoscope) are as follows: the scope is flexible in all directions along its central or longitudinal axis; it has a length of about 164 cm and a diameter of about 14.2 mm; the scope includes a fiberoptic viewing channel and fiberoptic light pipes, and a depth of focus of about 5–100 mm; controllable tip deflection of the scope is 180°/180° up/down and 160°/160° right/left; and one or more air and water delivery channels provided in scope. In addition, a conventional scope typically includes one or more open channels for insertion of instruments for suction, biopsy, surgical incisions, injections, sonography, laser therapy, etc.
For reasons of safety, comfort to patients, and reduction of time and costs of colonoscopic (and enteroscopic) procedures, a system which would allow automated retrograde introduction of endoscopes that followed the course of the bowel lumen would be highly beneficial. When fully introduced in a timely fashion, existing fiberoptic colonoscopes are remarkably effective instruments for a variety of diagnostic and therapeutic interventions. Over the past two decades, commercial developments have produced small incremental improvements in the endoscopes and the instruments that are fed through their channels. The one major innovation over recent years has been the introduction of scopes by the Olympus Corporation that allows for selective increases of rigidity of its segments; this has been demonstrated (Brooker, J. C. et al.: Gut; June, 2000: 46:801–805) to be very helpful to the “proximal-push” mechanism which has been and presently remains the main mode for state-of-the-art propulsion of endoscopes. Nonetheless, many investigators have recognized continuing need for and have attempted to augment the proximal-push forces with other means to facilitate delivering the endoscope to the entire target area.
The related art reveals a variety of approaches that have been taken to improve the safety, efficacy, comfort, and efficiency of colonoscopy. Examples of some different approaches to enhance the design of an endoscope can be seen in U.S. Pat. Nos. 4,054,128, 4,389,208, 4,991,957, 5,353,807, 5,482,029, 5,645,520, 5,662,587, 5,759,151, 5,819,736, 5,906,591, 5,916,146, 5,984,860, 5,996,346, 6,162,171, 6,293,907, 6,309,346, 6,315,713 and 6,332,865. The disclosures of these patents are incorporated herein by reference in their entireties. The efforts to deliver the working end of endoscopes to the sites required for complete examination or treatment of the colon and small bowel have included several different modalities for physically transporting the endoscope into the patient. Yet, the clinical state-of-the-art for colonoscopy has rested on the decades old “proximal-push technology” as its mainstay, with the recent major improvement offered by introduction of scopes by the Olympus Corporation that allow for selective increases of rigidity of its segments. Otherwise, technical improvements of colonoscopes themselves have been small and incremental; nonetheless, the net result of the numerous small improvements over the years is the current availability of colonoscopes that are technical marvels. Illumination and visual fields; flexibility of the body; universal flexible directional control of the distal end of the scope; air and water jet delivery channels; one or more small to large channels for insertion of instruments to provide suction, biopsy, injections, incisions, sonography, laser therapy, etc., etc. attest to the great versatility and effectiveness of this modality in management of gastrointestinal disease. Indeed, the proliferation of many sophisticated instruments which are introduced via the scope's channels has so greatly increased the usefulness of colonoscopy that the lack of more major improvements in its own intrinsic technology has been comfortably tolerated.
What are the important improvements in current state-of-the-art colonoscopy that cry out for attention and solution? Mostly they revolve about the ease, comfort, safety and rapidity of introduction and traversing of the entire colon for the intended diagnostic and/or therapeutic purposes. By synthesizing the information in the many patents listed above, the following points can be observed:
1. Major efforts have been expended and are under way to devise innovative methods for transporting the endoscope to where it needs to be with appropriate control, timeliness, safety, ease and comfort; this confirms the importance of these continuing needs.
2. The proximal-push mechanism is central and necessary for propelling a colonoscope, but it is not fully sufficient. Many investigators have deliberately attempted to augment the proximal-push with other forces to propel the colonoscope to meet the described needs.
3. It is becoming progressively more difficult to clearly identify the boundaries between technical support of medical/surgical clinical gastroenterology and the robotics supporting minimally invasive surgery (MIS).
4. In the attempts to innovate more effective endoscopic instruments, some investigators have developed instruments that come to look less and less like current endoscopes. Many have substituted new complicated technologies that are not superior to current colonoscopes to supplant existing scopes rather than creating new systems that can utilize the very mature, superb existing scopes. Many proposals rely on moving parts gaining traction against the bowel wall, or pushing on the wall, or that use pneumatic suction to adhere to the wall, all of which may alter or injure the mucosa. Others significantly increase the bulk of instruments that are inserted into the colon.
From these disparate considerations, a new vision crystallized: An improved propelling mechanism for the colonoscope should not sacrifice any meaningful characteristics of today's state-of-the-art colonoscope. This dictates that an innovative propelling mechanism must be engrafted upon today's existing scopes; an innovative propelling mechanism should be implemented which requires no or relatively few structural changes of existing colonoscopes, where any changes are so minimal as not to disturb any of their present attributes.